Application of 1,2-dimethoxy-4-nitro-benzene and 1,4-dimethoxy-2-nitro-benzene as overcharge protection additives in lithium-ion batteries

Abstract

1,2-Dimethoxy-4-nitro-benzene (DMNB1) and 1,4-dimethoxy-2-nitro-benzene (DMNB2) were selected as new redox shuttle additives for overcharge protection in lithium-ion batteries. The base electrolyte is 1 mol·L -1 LiPF 6/(ethylene carbonate (EC)+diethyl carbonate (DEC)+ethyl-methyl carbonate (EMC) (1:1:1, by volume)). Cyclic voltammetry (CV), charge-discharge cycle performance, overcharge tests, electrochemical impedance spectra (EIS), and scanning electron microscopy (SEM) were used to investigate the electrochemical performances of DMNB1 and DMNB2. The overcharge protection of DMNB1 and DMNB2 on lithium-ion batteries and the compatibility of both additives with the LiNi 1/3CoMn 1/3O 2 electrode have been studied. The results show that the working potentials of the both additives are above 4.3 V (vs Li/Li +), and thus are suitable for overcharge protection in lithium-ion batteries. Lithium-ion batteries with DMNB1 and DMNB2 have an improved overcharging tolerance. DMNB1 shows better overcharge protective performance, in the 100% overcharge and 5 V cutoff voltage tests, than DMNB2. After 100 cycles at 0.2C rate, the capacity retention rates of the LiNi 1/3Co 1/3Mn 1/3O 2/Li cells with the base electrolyte and the electrolyte with DMNB1 and DMNB2 are 98.4%, 95.9%, and 68.1%, respectively. The electrochemical properties and the location of the nitro-group on the benzene of the overcharge protection additives are closely linked. © Editorial office of Acta Physico-Chimica Sinica.